Lymph nodes filter lymphatic fluid that flows from the body’s tissues. This fluid may contain cancer cells, especially if the fluid drains a part of the body containing a tumor. By surgically removing and examining the lymph nodes that drain a tumor, doctors can sometimes determine if a cancer has spread.

Lymphoseek is an imaging drug that helps locate lymph nodes; it is not a cancer imaging drug. Lymphoseek is the first new drug used for lymph node mapping to be approved in more than 30 years. Other FDA-approved drugs used for lymph node mapping include sulfur colloid (1974) and isosulfan blue (1981).

“Removal and pathological examination of lymph nodes draining a primary tumor is an important diagnostic evaluation for some patients with breast cancer or melanoma,” said Shaw Chen, MD, deputy director of the Office of Drug Evaluation IV in the FDA’s Center for Drug Evaluation and Research. “To use Lymphoseek, doctors inject the drug into the tumor area and later, using a handheld radiation detector, find lymph nodes that have taken up Lymphoseek’s radioactivity.”

Lymphoseek’s safety and effectiveness were established in two clinical trials of 332 patients with melanoma or breast cancer. All patients were injected with Lymphoseek and blue dye, another drug used to help locate lymph nodes.

Surgeons subsequently removed suspected lymph nodes for pathologic examination. Confirmed lymph nodes were examined for their content of blue dye and/or Lymphoseek. Results showed Lymphoseek and blue dye had localized most lymph nodes, although a notable number of nodes were localized only by Lymphoseek.

The most common side effects identified in clinical trials was pain or irritation at the injection site.

Lymphoseek is marketed by Navidea Biopharmaceuticals, Inc. based in Dublin, Ohio.

The FDA, an agency within the U.S. Department of Health and Human Services, protects the public health by assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices. The agency also is responsible for the safety and security of our nation’s food supply, cosmetics, dietary supplements, products that give off electronic radiation, and for regulating tobacco products.